When exporting from InDesign 5.5 to PDF, all colors don't automatically appear unless Acrobat's Page display is set to Use Overprint Preview Always -- which isn't the default. How can I export so the PDF displays all colors without users having to modify Acrobat settings?
Export as a PDF/X file (PDF/X-1a, PDF/X-3, PDF/X4). With a PDF/X file, Acrobat or Reader turns on Overprint Preview even if the Output Preview panel is not open. (When Output Preview panel is open, Overprint Preview is turned on by default.)
That seems to have solved the problem. You rock!